In a tough new ad and in his attacks at last week’s debate, Senator Scott Brown has stoked questions about ­Elizabeth Warren’s professed Native American ancestry. But the difficulty of seizing on the controversy without crossing into uncomfortable racial territory became apparent Tuesday with the release of a video showing Republican staff members, including an aide in Brown’s Senate office, performing tomahawk chops and war whoops outside one of his campaign events.

Brown said such behavior is “not something I condone,” but declined to apologize.

“The apologies that need to be made and the offensiveness here is the fact that Professor Warren took advantage of a claim, to be somebody, a Native American, and used that for an advantage, a tactical advantage,” Brown said.

The video, released by the state Democratic Party, was part of a concerted effort by Democrats to argue that Brown and his campaign have crossed a line for political gain.

“Scott Brown and his staff are launching outrageous and offensive personal attacks to distract from the issues that matter,” said Matt House, a Massachusetts Democratic ­Party spokesman. “The behavior of his staff is completely ­inappropriate, but the tone of the campaign is set by the candidate.”

Warren said she was ­“appalled” by the video. “If this had happened on my staff, there would be consequences . . . serious consequences,” she said at an appearance with union workers. She declined several chances to elaborate.

Warren, who bases her asser­tions of Native American ancestry on family stories, has acknowledged that she listed herself as a minority in a legal directory often used by law school recruiters. But she has insisted she never received any professional benefit because of that assertion, a statement supported by those who hired her at Harvard Law School and other institutions.

In the video, filmed by a Democratic tracker Saturday outside a Brown event at the Eire Pub in Dorchester, the Brown staff members can be heard whooping and be seen making tomahawk motions amid a crowd of boisterous supporters of both candidates. The state Democratic Party identified the staff as Brad Garnett, who works for the Massachusetts Republican Party, and Jack Richard, a constituent services lawyer in Brown’s Senate office. Brown’s campaign neither confirmed nor denied the identity of those in the video.

The video’s release came a day after Brown began airing a new ad, in which he plays clips of news reports about Warren’s undocumented claim of Native American ancestry. And in last week’s debate, Brown made an apparent reference to Warren’s appearance in an attempt to demonstrate that she is not ­Native American.

“Professor Warren claimed that she was a Native American, a person of color,” Brown said. “And, as you can see,” he continued, gesturing toward Warren, “she’s not.”

Suzan Shown Harjo, president of the Morning Star Institute, a Native American rights organization, said she was dismayed by the way Brown and Warren have handled the ­ancestry issue in the campaign.

Harjo said it is legitimate for Brown to question Warren’s claim of Indian ancestry, but not appropriate for him to dismiss it by pointing to Warren’s appearance.

“It’s not about skin color,” said Harjo, a citizen of the Cheyenne and Arapaho tribes. “It’s not about your eye color or hair color. It’s about whether or not you’re a citizen of the ­nation you claim.”

Harjo said she was also disturbed by the video showing Republican staff members making war whoops and chopping motions.

“It’s a throwback to the Indian-­as-savage era and another good reason we have to get rid of all these dumb sports stereotypes about Native people because they carry with them attitudes and behaviors of racism that exist just below the surface in America,” she said.

By the same token, she said, it is wrong for Warren, in a new ad she released Monday in ­response to Brown’s attacks, to point to her family stories as evi­dence of her Native American roots. “It doesn’t matter what anyone thinks about Elizabeth Warren being Native American,” Harjo said. “What matters is, is she is a citizen of the Cherokee and Delaware ­nations? And they have not claimed her, and she cannot support that.”

On Tuesday, Brown denied he was suggesting Warren’s appear­ance proves she is not Native American, despite his pointed reference to her appear­ance during the debate.

“I never made that suggestion at all,” he said. “You guys have made the reports. I didn’t create the story. This is a story of her own making. She self-reported that she was a Native American and a minority, and there’s no evidence through ­genealogical efforts and through any other efforts at all that she is. Clearly, she’s not.”

News of the video was the lead item Tuesday on the website of Indian Country Today Media Network, a Native American news service, which reported: “The ugly side of this issue, racist imagery, has been with the campaign for months, just under the surface.”

Brown insisted the Native American issue is not critical to his reelection strategy.

“No, no, no, but it’s certainly an issue,” he said. “The ad that we’ve run is a fair ad. It’s accurate. It’s reflective of what you all have said for months now, that she needs to come straight . . . it goes to her character.”

Peter Ubertaccio, a Stonehill College political scientist who has followed the campaign closely, said questions about Warren’s ancestry are legitimate. But Brown may be losing ground by continuing to go ­after the issue because many whose votes are likely to be influ­enced by the issue already know about it. And the video, he said, did not help.

“When you’ve got your own people engaging in an activity that can be viewed as racially insensitive, then you run a real risk of turning off people, as ­opposed to bringing them to your side,” he said.

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